Hot melt adhesives are widely used in industry for various packaging applications. Most such applications, require that the adhesive have a fast set time, good machinability, and good bond aging characteristics. In addition, it is desirable that the adhesive maintain bonds over as broad a temperature range as possible.
Most hot-melt packaging adhesives are based on polyethylene or ethylene-vinyl acetate copolymer. Polyethylene and chemically modified polyethylene based formulas tend to have excellent elevated temperature properties, while ethylene-vinyl acetate based adhesives tend to have very good low temperature properties. The choice of which of these two adhesives sometimes depends upon the needed properties of the final end use. Blending of polyethylene or chemically modified polyethylene with ethylene-vinyl acetate to obtain broader temperature properties is often not very effective because of compatibility problems. Therefore, a hot-melt adhesive for packaging applications having a good bond strength over a broad temperature has not been possible.
In light of the above, it would be very desirable to be able to produce a hot-melt adhesive for packaging applications having a fast set time and a good balance of properties while maintaining good bond strength at elevated temperatures and low temperatures.